To emphasize your point, if it is in the public domain, by definition they already own it, and your suggestion that they purchase an e-reader would make access to their ownership of extensive cultural capital that much more accessible.

I realize that there is a lot of frustration regarding e-readers, but this is already the primary reason I own one-- to access the books which already belong to me in the public domain so that I don't need to pay for them again just to read them. On the other hand, I generally won't purchase copyrighted books for my e-reader because I won't own it like I would a physical copy.